Sex does everything! If your sick, sex will cure you. Depressed? Sex will fix it. Tired? Sex will give you energy. Can't sleep?Sex will relax you. I don't know if it will heal a bullet wound, but I'm sure my husband would swear it would.  
If a close friend , relative or pet dies......Sex will bring you comfort and peace. 
Sex also makes holidays more special. If it's your birthday. Celebrate with sex. Anniversaries(weddings , deaths, the dog having her first litter of pups), New Years , Christmas, Valentine's, Labor Day, Opening Day of deer season. Any little obscure notation on the calendar needs to be acknowleged with sex if possible. 
Sex is the reason you wore those sweat pants and that worn out old shirt (you know you feel so sexy in those rubber gloves too!) 
The reason you went in for your post baby/ post op check-up was not to find out if it was OK that you were back to cleaning and cooking and lifting kids and lugging laundry around the second you came home........ it was to see if it was OK to have sex.  
Some gals I know have told me they had sex with their man : the day after delivery with stitches, first day home from gallbladder surgery with drain tubes! , and when HE was down in his back so bad he could't get out of bed to pee. Now there's dedication! 
If I cut my leg half off and came in to get a ride to the emergency room my husband would probably say, "HEY!!!!!!!! You're looking awful hot in that tourniquet. Think we might need to get a quickie in before we leave." (Who knows it might spontaneously heal! Then we can celebrate! Wink wink. ) 
When he tells me there's something wrong with me because we don't have sex 4 or 5 times a week like most married couples do, I ask him which issue of Penthouse he got that stat. from because I don't know of any women, ( except Peg Bundy from "Married With Children") who have the energy to chase it down that much.(BTW She did no housework or real parenting so of course she was rested, and the 5 lbs. of chocolate she ate during "Oprah" every day probably had her stoked!!) 
And in conclusion Sex = Love....to a lot of men, and there is no amount of catering to, feeding , clean underwear, kind words, being there for and backing them up that will confirm your love any better. I know. I've had seventeen years of material to refer back to. And you better believe Dr. Phil when he said "Women have a looonngg memory".